A conventional linear motion mechanism includes a motion member and an axial rail member, wherein each of the motion member and the rail member provides at least one rail and the two respective rails are located corresponding to each other. A series of rolling elements are movable between and in contact with the rails. The motion elements provide a return passage and two direction changing passages to each of the rails corresponding thereto. The direction changing passages are connected to the straight return passages, the entry of the rail and the exit of the rail to form the circulating passage so that the rolling elements enter the return passage via the direction changing passage and then enter the other rail via the return passage and the direction changing passage. The rolling elements are movable within the circulating passage, and the movable member is movable along the rails by the rolling elements.
In order to avoid from impact between the rolling elements, U.S. Pat. No. 5,927,858 discloses separators between the rolling elements. However, there is clearance between the separators and the rolling elements so that the separators tend to be tilted and shifted, such that the separators interfere with the circulating passage and affect the motion of the rolling elements.
U.S. Pat. No. 5,947,605 and U.S. Pat. No. 6,155,718 disclose a rolling element retainer belt which has two axial and thin strips and the separators are connected to the strips, and the rolling elements are located and retained between the separators. The belt is an elongate, flat and flexible, so that the belt can be deformed in the direction perpendicular to the plane composed of the two strips and the plane is named the plane of the belt. However, the belt has higher stiffness in the perpendicular direction so that resistance is generated when deformed in the perpendicular direction. Accordingly, the rolling element retainer belt is suitable for being operated on the plane that is perpendicular to the plane of the belt and suitable for being deformed on a two-dimension plane. When the circulating passage is not located on the plane, the belt has to deform toward the direction that is inclined to the belt, and has to overcome the resistance in the perpendicular direction. In other words, the belt has to overcome the resistance when deforming toward the perpendicular direction. Thus, the rolling element retainer belt cannot move smoothly.
Taiwan Patent No. 1273185 discloses a rolling element retainer belt which improves the inherent problems of the above-mentioned conventional rolling element retainer belt, and comprises multiple rolling elements and a belt which provides multiple holes in which the rolling elements are accommodated. The retainer belt includes multiple separators which separate the adjacent rolling elements. At least two thin and elongate resilient strips are connected to two ends of transverse resilient belts. The transverse resilient belts are connected to the separators at the mediate portions thereof. The transverse resilient belts are ensured to have the longest length and sufficient flexibility and can be deformed toward two opposite directions. The separators can be rotated and tilted in different directions relative to the transverse resilient belts. The rolling element retainer belt has sufficient degrees of freedom to change direction in the three-dimensional circulating passage so as to be smoothly operated with less resistance.
However, the two ends of the transverse resilient belts connected to the resilient strips, and the separators connected to the transverse resilient belts provide the retainer belt with higher degrees of freedom when deforming. However, because the connection area between the separators and the resilient belts are limited, the structural strength may not be sufficient when the retainer belt continuously turns. Furthermore, the clearance between the rolling elements and the resilient belts makes the rolling elements shift and the resilient belts cannot position the rolling elements.
The present invention intends to provide a rolling element retainer belt which has a mounting surface for mounting the rolling elements so that when the rolling element retainer belt turns continuously, the rolling elements are well positioned and the retainer belt deforms properly to overcome the resistance when the turning.